So I would encourage people with maths interest to go sideways rather than upwards - geometry, not calculus. You can calculate compound interest geometrically. Probability as a whole didn’t exist in the middle ages and likely doesn’t exist in its modern form IC. The scientific method doesn’t work on long timebases in the Empire setting - inferential logic itself isn’t quite valid because of conjunctions, and the mere process of using mathematical methods to approach a problem may perturb it.
Any answer you did get to questions about this would not be coming from a position of lack of expertise, though - of that I can assure you.
Leviathan, for example, isn’t running a statistical model of the world for those Asimov-be-plagiarised psychohistorical observations - Leviathan IS WATCHING and IS AN EXPERT.
But if you wish to call upon f/ex Ylenrith using goetia, I strongly suggest mathematics as a decent way to do it.
I guess the question is - what are you trying to do with the maths?
See also the following quote, which I love for all fantasy settings everywhere:
Neo: “Doesn’t harvesting human body heat for energy violate the laws of thermodynamics?”
Morpheus: “Where’d you learn about thermodynamics, Neo?”
Neo: “In school.”
Morpheus: “Where’d you go to school, Neo?”
Morpheus: “The machines tell elegant lies.”